1. Field of the Invention
The present invention relates to a method of manufacturing and apparatus for manufacturing an irregular shaped cross section tube and to the resulting irregular shaped cross section tube.
The present invention further relates to a method of manufacturing and modular tool die for manufacturing irregular shaped cross section tubes and the resulting irregular shaped cross section tubes.
The present invention relates to a method of manufacturing an irregular shaped cross section tube structure and a die with a removable, integral mandrel that forms tubular structures having irregular cross sections without hydroforming, and to the resulting irregular shaped cross section tubes.
The present invention relates to a method of manufacturing and apparatus for manufacturing an elongated tubular frame member with irregular cross section and localized work hardening to provide significantly improved crash force absorption when employed in vehicle construction, and to the resulting irregular shaped cross section tubes formed thereby.
The present invention further relates to a method of manufacturing a tubular member having an irregular cross section and apparatus for manufacturing a tubular structural member having an irregular cross section for use in a vehicle from a blank of metal wherein features, holes and localized hardening are made in the blank prior to forming the blank into a tubular structural member with irregular cross section.
2. Description of the Related Art
Small, U.S. Pat. No. 1,387,199 is directed to a method of making tubes or bushings of practically any length that comprises taking a metal blank of desired dimensions, bending a blank to a tubular form with the longitudinal edges in juxtaposition, then drawing the form so as to flow the metal and set the edge in closer firm abutting relation. The tube is formed by means of a pair of dies that gives the blank a U shape and then subjecting the U shaped blank to another set of dies to form a tube over a mandrel. The mandrel is inserted into the dies after the first operation of forming the blank into a U shaped blank. After the second forming event, the mandrel is removed and the tube is passed through another die of smaller dimension than the tube to force the edges of the tube together and cause the edges to become parallel. After the tube is removed from this die, the natural spring in the metal causes the edges to spring away from each other and tend to open the joint. A plug and die is used to force the edges of the tube into engagement with each other in a phenomenon termed arching to set the edges together.
The present invention does not depend upon arching to close the joint. The present invention is further capable of making a tube with an inverted cross section and bends. There is no showing that the invention of Small is capable of making tubes with inverted cross section.
Stolp, GB 129,983 discloses and apparatus and method for forming metal tubes from blanks of metal. The method includes forming a U shaped blank. A die is applied to the U shaped blank and an internal mandrel is then forced through the U shaped blank and the ends of the U shaped blank are bent around the mandrel in cooperation with the external forming dies to form a pipe having a cross section that matches the mandrel. Bending and creasing dies are used in successive fashion to finish the channel shaped member, still containing the internal mandrel, into a finished tube. The mandrel is then removed to form the tube.
Stolp differs from the present invention. Stolp does not include a mandrel integral with the dies. In addition, Stolp does not disclose making tubes with inverted cross sections having internally directed bends. Accordingly, the present invention differs from Stolp.
Black, U.S. Pat. No, 2,115,441 discloses a method of forming tubular structures from sheet metal, and particularly for use as frame members for truck bodies. Black describes a method for bending sheet metal into channels of various forms and angles without the use of mandrels leading up to a final die operation that bends the channel or semi formed tubular structure into a completed tube or semi-formed tubular structure from opposite sides and active on one side wall particularly through the open side of the channel.
Black differs from the present invention. Particularly, the present invention utilizes a mandrel to bend the metal in the die to assist in formation of a tube structure having and inverted irregular cross section. Black does not contemplate the formation of a tube with inverted cross section. In addition, the apparatus of Black does not include an internal mandrel to form the tube. Finally, there is no disclosure for forming a tube with inverted cross section and bends, such as is possible in the present invention.
Lowery et al, U.S. Pat. No. 5,657,922 discloses a method and apparatus for forming tapered, cylindrical poles from trapezoidal metal strips. The process is comprised of the steps of curling or pre-forming a trapezoidal blank, and then forming the preformed blank into a tubular shape by means of a shovel die. The tubular shaped blank is welded along a longitudinal seam such that a tubular pipe is formed. The resulting tapered cylindrical poles are used around highways, parking lots and playing fields to support lights or signs. The process can also be used to form thin walled cylindrical pipes.
Lowery does not disclose a method for forming a tubular structure with an inverted cross section, localized hardening, and bends. Moreover, the apparatus used by Lowery et al., does not include an internal mandrel integral with the die to form the tubular structure.